Container such as a nursing container, with flexible liner and access site and method of making said access site

ABSTRACT

A container is disclosed having a semi-rigid or rigid shell, a co-extensive flexible liner weakly or temporarily adhered to the shell and an access site defined in the container wall to which an access assembly may be attached. The access site is preferably defined by an annular fold in the container wall which tightly captures the liner to provide a mechanical peripheral seal between the shell and liner around the access site to prevent leakage of liquid, into the area between the shell and liner. The container is particularly useful as a nursing container, including a nipple access site with an attached nipple assembly.

The present invention relates, in general, to nursing containers forfeeding liquid to an infant. More particularly, the present inventionrelates to nursing containers of the type employing a flexible liner orpouch which is collapsible upon dispensing of the contents to an infant.

Nursing containers employing flexible liners or pouches have beenproposed in a wide variety of shapes and configurations, as exemplifiedby U.S. Pat. Nos. 3,117,874 to Horan; 3,537,225 to Fields; 2,628,909 toHoran; and 3,790,017 to Fitzpatrick et al. Perhaps the most well knownof these is the type of nurser shown in Fitzpatrick. The nurser depictedthere employs a reusable rigid sleeve or tube and a disposable plasticliner which may be secured to the end of the tube and held in place by aresilient nipple. While avoiding many of the difficulties associatedwith rigid containers, the most well known of which is the requirementof displacement air within the container to dispense the contents andpossible infant ingestion of that air such nursers, because they are notsterile, generally must be prepared on an as-needed basis, and require asubstantial amount of manual assembly and preparation. Although this maybe suitable for the home, is not convenient or preferred forinstitutional environments such as hospitals and nurseries.

Other proposed flexible nursing containers have different shortcomings.For example, U.S. Pat. Nos. 3,537,225 and 3,386,604 to Fields disclose adisposable infant container, and a relatively complex method for makingit, where the nipple is actually formed into the container wall, andmust be opened by piercing the nipple with a pin or similar instrument.For apparent protection during storage and shipment, after the pouch isfilled and sealed, its enclosed in an outer container or overpouch in anentirely separate operation. The pouch disclosed in Fields may beworkable, however, it is believed that the pouch is not generallypractical, and is not well suited to home or institutional use.Moreover, the two-stage manufacturing process to make the pouch andouter cover is complicated, and likely to result, it is believed, in arelatively costly product.

It is, accordingly, a general object of the present invention to providea nurser and a method of making a nurser which does not suffer from thedrawbacks described above.

It is a further object of the present invention to provide a nurserwhich employs a generally flexible fluid compartment wall that collapsesas liquid is dispensed and does not require the entry of displacementair into the container for dispensing to an infant.

It is a further object of the present invention to provide an infantnurser which is pre-filled and sterilized for institutional convenienceand improved shelf life.

It is a further object of the present invention to provide such acontainer which includes at least a semi-rigid outer shell portion forprotecting and supporting the flexible liner as well as for handlingconvenience.

It is a further object of the present invention to provide such acontainer with a nipple access site for accessing the contents of thecontainer.

It is yet a further object of the present invention to provide aconvenient and low cost method for making such a container and accesssite.

These and other objects and advantages of the present invention areachieved in a nursing container which has a substantially continuousouter semirigid or rigid plastic shell, a flexible plastic linerinterior of the shell and substantially coextensive therewith, aquantity of liquid, such as infant formula or water, within the liner,and a nipple assembly secured to the shell and adapted to providecommunication to the otherwise sealed plastic liner. An intentionallyand selectively weak or temporary bond is provided between the liner andshell to permit separation of the liner from the shell subsequent toformation of the nursing container, and upon dispensing of the liquidcontents from within the liner. The bond between the liner and shell maybe provided by a selected low tensile strength adhesive between theliner and shell materials, or by natural adherence between the plasticmaterials of the shell and liner or by electrostatic attraction betweenthe shell and liner. Such a container is specifically described andclaimed in co-pending application Ser. No. 599,302, entitled "ContainerSuch As A Nursing Container, With Flexible Liner And Method Of MakingSame" to J. Cabernoch which is being filed simultaneously herewith.

Preferably, the shell and liner are coextruded or laminated together inthe bonded condition, and it is only necessary that they adhere duringfabrication of the nursing container. After the container is formed,filled and sealed, it is not necessary that the liner and shell remainbonded together. Thus, a degradable adhesive may also be used betweenthe shell and liner to permit subsequent separation. In eitherembodiment, the resulting container provides a pre-filled pre-sterilizedinfant nurser which is particularly convenient to use, does not requiresubstantial on-site preparation, and has the advantage of a flexibleliquid container which permits dispensing of the contents to an infantwithout requiring displacement air.

In these embodiments, the contents may be accessed by a nipple assemblyattached to the shell which includes accessing means movable uponmanipulation of the nipple assembly to pierce the wall of the containershell and liner. In accordance with the present invention, to preventcontents from escaping into the area between the shell and liner whenthey are pierced, a special nipple access site provided in the containerwall where the liner is tightly sealed to the shell. Preferably, thenipple access site is defined by an annular fold formed in the containerwall which captures the liner mechanically to seal it to the shellaround the periphery of the access site and prevent liquid from flowingback between the liner and shell and hold the liner tightly to assurepentration by the nipple access member.

The present invention is not limited to a nursing container but may alsobe a container having an access assembly for delivery of a containedfluid in a manner such that the flexible liner collapses and such thatthe entry of displacement air is not required.

These and other objects and advantages of the present invention are setforth in the following detailed description of the attached drawingswhich depict various embodiments of the present invention for thepurposes of illustration, and not limitation, and of which:

FIG. 1 is a perspective view of a nursing container with dispensingnipple and cover, in a removed position, embodying the presentinvention.

FIG. 2 is a longitudinal cross-sectional view of the container of FIG.1, taken along line 2--2 of FIG. 1.

FIG. 3 is a cross-sectional view of the container of FIG. 1 taken alongline 3--3 of FIG. 1.

FIG. 4 is a cross-sectional view of the container of FIG. 1,illustrating dispensing of the contents through the nipple assembly, andcollapse of the liner wall as the contents are dispensed.

FIG. 5 is a diagrammatic illustration of the coextrusion of a plasticparison having a rigid outer layer and a flexible inner layer weaklyadhered together for use in the present invention.

FIG. 6 is a vertical cross-sectional view of molding apparatus forforming a coextruded parison into the desired nursing container.

FIGS. 7a and 7b are enlargements of the lower end portion of the moldsof FIG. 6, depicting sealing of the parison walls together by the molds.

FIG. 8 is a perspective view of an alternative embodiment of the nursingcontainer of the present invention, which is formed by folding agenerally planar sheet of coextruded or laminated plastic to form agenerally pouch shape.

FIG. 9 is a longitudinal sectional view of the container of FIG. 8 takenalong line 9--9 of FIG. 8.

FIG. 10 is a cross-sectional view of the container of FIG. 8 taken alongline 10--10 of FIG. 8.

FIG. 11 is an enlarged cross-sectional view of the nipple assembly andthe end of the container of FIG. 8 to which the nipple assembly isattached, showing a nipple assembly access site on the container.

FIGS. 12a-12c depict a method for forming a nipple access site in thecontainer wall.

Referring now to the drawings in general, the present invention isgenerally embodied in a nursing container 20 having an outer rigidplastic shell or layer 22, an inner flexible liner 24 in which liquid28, which may be an infant formula, water or the like, is contained anda nipple assembly 26 attached to the shell. In accordance with thepresent invention, the liner 24 is substantially coextensive with theouter shell 22 and weakly or temporarily bonded thereto, the bond beingsufficiently weak or degradable to permit collapse of the inner linerwall as contents are dispensed to an infant. This construction providesa sealed unitary container which may be aseptically filled or filled andsubsequently sterilized to provide long shelf life, while simultaneouslyhaving the convenience and benefits of a flexible container which doesnot require the entry of displacement air for dispensing the contents toan infant.

The liner and shell may be weakly or temporarily bonded together invarious ways. Preferably a low tensile strength adhesive is coextrudedor laminated between the liner and shell. Alternatively, the layers maybe held together by a natural adherence of the materials used for theliner and shell, or by an electrostatic attraction between the shell andliner. Yet a further alternative is the use of a degradable adhesivewhich holds the liner and shell together during fabrication but releasesthem later when the adhesive degrades. The degradation process may occurby way of time, or may be accelerated by exposure to heat or ultravioletlight, depending on the particular adhesive used.

The container of the present invention may be formed, for example, bycoextruding a parison having an inner plastic layer corresponding to thecontainer liner, an outer layer corresponding to the container shell,and a layer of selected adhesive or plastic therebetween. The parisonmay then be molded, such as by blow molding, to form the desiredcontainer shape, and the nipple assembly then attached to the end of thecontainer. Alternatively, the container may be formed of a generallyplanar coextruded or laminated sheet which is folded together and sealedon the sides and end to form a generally pouch-shaped container.

In either alternative, the sealed seams of the container are preferablyformed in a manner which is depicted in FIGS. 7a and 7b. As shown there,the plastic film is compressed together along the seam, until theportion forming the liner is forced from between the shell-forminglayers, which then seal together. This sealing technique thus permitscollapse of the inner liner from all directions, rather than simply acollapse of opposed portions of the liner together.

Turning now to a more detailed description of the drawings, FIG. 1depicts one embodiment of the nursing container embodying the presentinvention, as it might be formed by blow molding a parison. The shelland liner form a generally cylindrically shaped container, which mountsthe nipple assembly 26 at one end, and is sealed along a tail seal 30 atthe other end. The shell and liner preferably form a unitary closedliquid compartment 32 within which the liquid formula, water or otherliquid for infant feeding is contained. The liner 24 is disposed alongsubstantially the entire inner surface of the shell 22, in other words,is co-extensive with the shell. The liner 24 is preferably made of arelatively thin plastic film sufficiently flexible to collapse under thevacuum created by dispensing of liquid from the compartment 32.Preferably the liner is inert to infant nutritional liquid, and may bemade of materials such polyethylene, or a laminate of polyethylene andpolyvinylchloride and the like. While the liner may be made of a singlelayer of such material it may also be made of a composite material or alaminated film which includes an oxygen barrier to prevent substantialoxygen transmission to the liquid container in the compartment, therebyimproving shelf life.

The shell 22 is also made of plastic material, and preferably a materialwhich, when cooled, provides a semirigid or rigid protective shell forthe liner 24. The shell 22 is preferably sufficiently thick to preventinadvertent puncture of the liner during shipping and storing, as wellas to provide an oxygen barrier to prevent substantial access of oxygento the liquid contained within the liner. As with the liner, the shell22 may be made of a single material or may be a laminated or compositematerial including an oxygen barrier material, such as Saran plastic.Among the many materials suitable for shell material are polypropylene,polyethylene, and high impact polystyrene.

In accordance with the present invention, the liner and shell areformed, for example, by coextrusion or lamination, to have a selectivelyweak adherence which will hold the layers together at least duringcontainer formation, but permit the liner to collapse when the contentsof the container are dispensed. To achieve this, the adhesive materialpreferably has a very low tensile strength to permit separation of theliner and shell upon dispensing of the contents. For example, with ahigh impact polystyrene shell and a two layer laminated liner ofpolyvinyldichloride and medium density polyethylene, a suitable low bondstrength adhesive layer, such as an ultra low molecular weightpolyethylene may be provided between those materials. A wax-basedadhesive layer which permits ready separation of liner and shell andalso may be weakened upon heating of the container contents prior tofeeding of the infant, may also be used.

Alternative means for adhering the liner to the shell include the use ofan adhesive, the bond strength of which diminishes or weakens whenexposed to certain conditions. One advantage of such adhesive materialis that it permits a very strong bond during formation of the containerand the manufacturing steps involved therewith, yet provides that theliner is completely unbonded or unadhered to the shell by the time it isput to use. Various types of degradable materials, which degrade underdifferent conditions, may be used in accordance with the presentinvention. For example, some adhesives may degrade with age, or with theapplication of heat such as occurs in autoclave sterilization. Inanother type of adhesive, the degradation is activated by exposure toultraviolet light. Employing this adhesive, the finished container wouldbe exposed to ultraviolet light when manufacturing was complete,starting the degradation process which would permit the liner to readilyseparate from the shell when eventually used.

An alternative means for adhering the shell and liner together iselectrostatic force, wherein a selected electrostatic charge is appliedto each of the shell and the liner, resulting in attraction therebetweenwhich is sufficient to permit the shell and liner to adhere together atleast during manufacturing processing.

The container formed by the shell and liner is preferably a unitarysealed compartment, which may be either aseptically filled or filled andsubsequently sterilized. Yet it provides the convenience and safety of acollapsible liner, which permits the contents to be dispensed withoutleakage or fear of air ingestion by the infant.

For dispensing the contents, the nipple assembly 26 is sealed to one endof the container and includes integral means for accessing the contentsby piercing the container wall. One type of nipple assembly suitable foruse with the present invention is depicted, in cross-section, in FIG.11. As seen there, the nipple assembly 26 includes a flexible nipple 34preferably made of elastomeric material, such as thermoplastic rubber,Kraton G plastic of the Shell Chemical Company, silicone, or othermaterial. The nipple 34 has a generally radial base flange 36 which issealed to the outer shell 22. The nipple 34 has a side wall 38upstanding from the base flange, and terminating in a narrowerdispensing end portion 40 of the nipple, which has a dispensing apertureof 42 therein. The inside surface of the dispensing end of the nipple isgenerally spherical, to capture the spherical end of a puncturing spike44 disposed within the nipple. As shown in FIG. 11, the spike 44 is in aretracted position where it remains until the contents of the containermust be accessed. At that time, the spike is forced through thecontainer wall either by squeezing the dispensing end 40 of the nippleor by axially compressing of the nipple.

The puncturing spike 44 is generally elongated and hollow, terminatingin a tapered lower end 46. The spike has an interior passagewayextending upwardly through the center of the spike and communicatesthrough the lower end of the spike with elongated side apertures 50.

A cross-sectional view of the container alone, showing the opening spikein an extended liquid-accessing position is illustrated in FIG. 4. ThatFigure demonstrates the initial collapsing of the container walls asliquid is dispensed to an infant through the nipple. A more detaileddescription of the nipple assembly 26 used in the present invention andalternative embodiments of such nipple assembly is contained inco-pending U.S. application Ser. No. 599,305, entitled "Self-OpeningNipple Construction and Nursing Container", in the name of Leonard A.White, which is being filed simultaneously herewith.

For protecting the nipple assembly 26 in shipment and storage, and forpreserving the sterility of the nipple surface, a cover 52 is preferablysealed over the nipple. As shown in FIGS. 1, 8 and 11, the cover 50 isgenerally of rigid platic construction, and includes a generally radialbottom flange 54 which is heat sealed to the upper surface of thecontainer shell 22. Preferably, the heat seal between the flange 54 ofthe cover and the shell is frangible to permit easy removal of the coverby exerting a force on pull tab 56 of the cover.

Although the nipple assembly 26 may be secured to the container in avariety of ways, FIGS. 1-3 depict a mechanical attachment of the nippleassembly to the end of container. As shown in FIGS. 2 and 3, bottomflange 36 of the nipple assembly is mechanically captured, andpreferably thermally bonded, to the container wall. More particularly,the container has a reduced diameter portion 57 which forms a radialshoulder 59 that the nipple flange engages against. Preferably thematerials of the nipple and container wall are sufficiently compatiblethat the flange may be thermally bonded to the wall. To assureattachment to the container, the end portion 61 of the container wall isformed, as by heat swaging, or other suitable method, to tightly lockthe nipple to the container. In this embodiment a separate membrane 63may be sealed to the underside of the nipple flange to isolate thenipple and spike from the container contents and prevent leakage duringshipping and storing.

FIGS. 5-7b depict one method by which a container embodying the presentinvention may be constructed. Diagrammatically shown in FIG. 5 is acoextruder die 72 of a type well known in the art for extruding aplastic parison 74 comprising layers of various plastics and othermaterials fed to the coextruder from extruders nos. 1, 2 and 3. Forexample, extruder no. 1 could be the extruder for the plastic materialforming the rigid shell 22. Extruder no. 3 would be the extruder for theplastic material forming for the flexible liner material 24, andextruder no. 2 would be the extruder for the adhesive or bondingmaterial, if any, between the liner and shell. To actually form acontainer of the desired shape, the parison 74 is positioned, eitherdirectly from the coextruder, or after cooling and reheating, between apair of molds 76 (FIG. 6), which, when joined, define a mold cavity 78of the desired container shape. The parison is expanded to conform tothe cavity shape by injecting compressed air, or applying a vacuum tothe wall of the parison, or a combination of both. As shown in FIG. 6,the lower end of the molds 22 have pinch edges 80 which closesubstantially together when the mold closes, to form the tail seal 30 ofthe container. Of course, the bottom of the container could remain openfor filling and be subsequently closed by a heat sealing operationsimilar to that described hereinafter. Also, the nipple assembly may besealed to the container either in place within the mold, or subsequentto cooling. Preferably apparatus, not shown, is employed with the moldsubsequently to form the annular nipple access site on the end of thecontainer. Also, means such as a retractable pin may be utilized to formsmall port 81 (FIGS. 1-3) in the outer shell only, which allows air toenter the shell as the contents are dispensed and the liner collapses.

FIGS. 7a and 7b depict the formation of the tail seal 30 of a containerof the present invention, formed by blow molds 76. FIG. 7a depicts thelower edges 80 of the molds coming together and compressing the end ofthe container together. In that position, the inner liner 24 has comeinto contact between the tail seal portions of the outer shell 22. Asthe molds close completely, the portion of plastic material forming theinner liner is forced from between the shell portions, as shown in FIG.7b. With this construction, the end portion of the liner at the seal isnot trapped between the joined shell portions, and thus the entire lineris collapsible toward the dispensing nipple as liquid flows therefrom.Although this is not required for satisfactory container operation, itis considered desirable.

An alternative embodiment of the nursing container, is disclosed inFIGS. 8-10, which depict a container formed from a generally flat sheetof plastic material coextruded or laminated of a shell layer 22 and aliner layer 24. To form the container depicted in FIG. 8, the nippleassembly 26 is attached generally to the center of the sheet (not shown)and the sheet is folded until the end portions of the sheet meet. Thelateral edges of the sheet are sealed along lines 82, leaving the endopposite the nipple open for filling. Upon completion of filling, theend of the container is closed and sealed at 84, thereby providing acomplete sealed unitary container and nipple assembly arrangement.Preferably, the lateral seals 82 and end seal 84 of the container ofFIG. 9 are carried out in a manner such as that previously depicted anddescribed in FIGS. 7a and 7b, which force the liner portion from betweenthe shell, to permit collapse of the liner in all directions as liquidis dispensed through the nipple assembly 26.

Because the inner liner is intentionally easily separable from theshell, in other embodiment of the container, such as that depicted inFIGS. 8-10, the nipple assembly 26 is preferably attached to the shellat an access site in accordance with the present invention, which willpermit a puncturing member to access the container, without causingdelamination of the liner and shell in that area which would permitliquid contents to escape into the space between the liner and shell. Toprevent this, the nipple is attached to an access site, generallydesignated 58 at the end of the container. While the access site may beprovided by utilizing a permanent adhesive or bonding between the shelland liner in that area of the container, the access site is preferablydefined by a generally annular fold 60 in the container wall whichtightly entraps the liner and seals it to the shell peripherally aroundthe access site so that liquid cannot escape into the space between theliner and shell. More particularly, the fold, as shown in enlargedcross-section in FIG. 11, is actually formed by a pair of 180° folds inopposite directions, so as to define a generally S-shapedcross-sectional configuration. As shown in FIG. 11, the container wallis folded through 180° at 62 to bring the liner portions 64 into agenerally face-to-face relationship and tightly trap them between thefacing shell portions 66 and 68. A return 180° fold of the containerwall is provided at 70 such that the container wall continues in theoriginal direction. Thus, although the portion of inner liner maydelaminate or separate from the shell in the immediate area of theaccess site enclosed by the annular fold, the capture of the inner linerbetween folded portions of the shell mechanically seals the liner to theshell and prevents liquid from entering the space between the liner andthe shell.

Otherwise, the construction of the container shell 22 and liner 24 ofFIG. 8, the particular materials involved, and the operation of thenipple assembly, is essentially the same as that for the embodimentdepicted in FIGS. 1-4, and thus, for convenience, will not be repeated.

FIGS. 12a-12c depict the preferred method for forming the nipple accesssite and container in a sheet, to form the container depicted in FIG. 9.A portion of the sheet, having a laminated or coextruded shell layer 22,liner layer 24 weakly temporarily bonded together is depicted in FIG.12a prior to any of the formation steps for defining an access site.

In the first step of the process to define a nipple access site, agenerally annular V-shaped groove 88, having an inner wall portion 90and an outer wall portion 92, is formed in the sheet, such as bythermoforming, circumscribing the intended nipple access site 58. TheV-shaped groove is preferably defined to protrude toward the liner sideof the sheet, i.e., downwardly in FIG. 12b. The walls 90 and 92 formingthe V-shaped groove are then heat-swaged in a radially outwarddirection, capturing the portions 64 of the liner tightly betweenadjacent folded portions 66 and 68 of the shell. To accommodate thefolding arrangement, a generally raised rib 94 is preferably formedadjacent and outwardly of the V-shaped groove, so as to better definefold line 62 of the container wall during the swaging operation.Simultaneously with or subsequent to formation of the access site,clam-shell shaped sidewall portions 95 are thermoformed into the sheet.After the swaging operation is complete, the nipple 34 is thenheat-sealed to the shell at the access site circumscribed by the annularfold, and the clam-shell sides are folded together along thermoformeddimple 97 and the sides 82 sealed together. The end 84 remains opentemporarily for filling, and after filling is sealed to provide aunitary sealed container.

Although the present invention has been defined in terms of thepreferred alternative embodiments, the present invention, as defined inthe appended claims, includes those equivalent structures which may bereadily apparent, or which may be apparent to persons skilled in the artonly after some study.

What is claimed is:
 1. A nursing container comprising:a substantiallyrigid outer shell; a co-extensive flexible inner liner selectivelyadhered to said outer shell and separable therefrom; a nipple accesssite defined in said shell and liner; a nipple assembly sealed to saidcontainer at said access site; said access site being defined by acontinuous circumferential fold in said shell and liner tightlycapturing said liner to prevent inadvertent delamination of said lineroutwardly of said fold upon rupture of said access site.
 2. A nursingcontainer in accordance with claim 1 further comprising a dispensingnipple assembly attached to said access site and including means forrupturing said access site upon manipulation of said nipple assembly. 3.A nursing container in accordance with claim 1 wherein said foldcomprises at least one fold of said wall portion to define two segmentsof said wall portion in overlying relationship with a portion of saidliner captured in a face-to-face relationship therebetween.
 4. A nursingcontainer in accordance with claim 1 wherein said fold iscross-sectionally S-shaped.
 5. A nursing container in accordance withclaim 4 wherein said S-shaped fold is tightly compressed to secure saidliner.
 6. A method of providing a nipple access site in a nursingcontainer wall portion comprising a substantially rigid outer plasticlayer and a flexible inner plastic layer adhered to said outer layer andseparable therefrom, comprising:forming a continuous groove in said wallportion inadvertent toward said flexible layer; folding the wall portiondefining said groove to mechanically capture said inner layer therealongto define said access site in the area of said wall portioncircumscribed by said folded wall portion.
 7. A method in accordancewith claim 6 wherein said groove is generally V-shaped, and said step offolding comprises swaging said the wall portion defining said grooveinto a generally flattened configuration.
 8. A method in accordance withclaim 7 further comprising forming a raised annular rib around saidgroove.
 9. A method in accordance with claim 6 wherein said step offorming is conducted when said plastic is at an elevated termperature.10. A method in accordance with claim 6 wherein said groove is generallyV-shape.
 11. A method in accordance with claim 6 further comprising anipple assembly sealed to said outer plastic layer in the area of saidwall portion circumscribed by said folded wall portion.
 12. A method inaccordance with claim 11 further comprising sealing a cover over saidnipple assembly.
 13. A container for fluid comprising:a substantiallyrigid outer shell; a co-extensive flexible inner liner selectivelyadhered to said outer shell and separable therefrom; an access sitedefined in said shell and liner; an access assembly sealed to saidcontainer at said access site; said access site being defined by acontinuous circumferential fold in said shell and liner tightlycapturing said liner to prevent inadvertent delaminatin of said lineroutwardly of said fold upon rupture of said access site.
 14. A containerin accordance with claim 13 further comprising a dispensing memberattached to said access site and including means for rupturing saidaccess site upon manipulation of said dispensing member.
 15. A containerin accordance with claim 13 wherein said fold comprises at least onefold of said wall portion to define two segments of said wall portion inoverlying relationship with aportion of said liner captured in aface-to-face relationship therebetween.
 16. A container in accordancewith claim 13 wherein said fold is cross-sectionally S-shaped.
 17. Acontainer in accordance with claim 16 wherein said S-shaped fold istightly compressed to secure said liner.
 18. A method of providing anaccess site in a container wall portion comprising a substantially rigidouter plastic layer and a flexible inner plastic layer adhered to saidouter layer and separable therefrom, comprising:forming a continuousgroove in said wall portion; and folding the wall portion defining saidgroove to mechanically capture said inner layer therealong to definesaid access site in the area of said wall portion circumscribed by saidfolded wall portion.
 19. A method in accordance with claim 18 whereinsaid groove is generally V-shaped, and said step of folding comprisesswaging said the wall portion defining said groove into a generallyflattened configuration.
 20. A method in accordance with claim 19further comprising forming a raised annular rib around said groove. 21.A method in accordance with claim 18 wherein said step of forming isconducted when said plastic is at an elevated temperature.
 22. A methodin accordance with claim 18 wherein said groove is generally V-shaped.23. A method in accordance with claim 18 further comprising an accessassembly sealed to said outer plastic layer in the area of said wallportion circumscribed by said folded wall portion.
 24. A method inaccordance with claim 23 further comprising sealing a cover over saidaccess assembly.